The oxidation of AuCu nanoparticles was studied as a function of composition and temperature. Oxidation rates at 110 °C were higher for NPs with higher Cu content, showing that Au stabilized the Cu. Electrochemistry measurements show that AuCu could be a promising catalyst for lowering the over potential of CO(2) reduction.

The patterns formed by self-assembled thin films of blended cylindrical and lamellar polystyrene-b-poly(methyl methacrylate) block copolymers can be either a spatially uniform, single type of nanostructure or separate, coexisting regions of cylinders and lamellae, depending on fractional composition and molecular weight ratio of the blend constituents. In blends of block copolymers with different molecular weights, the morphology of the smaller molecular weight component more strongly dictates the resulting pattern. Although molecular scale chain mixing distorts microdomain characteristic length scales from those of the pure components, even coexisting morphologies exhibit the same domain spacing. We quantitatively account for the phase behavior of thin-film blends of cylinders and lamellae using a physical, thermodynamic model balancing the energy of chain distortions with the entropy of mixing.

The electrochemistry of anodic oxygen evolution on iridium in silicate-containing molten oxides at 1570 °C was experimentally investigated using both direct and alternating current methods. Static and rotating electrode results show the presence of anodic reactions of iridium in addition to oxygen evolution. In the context of electrochemical engineering of molten oxide electrolysis, the results confirm prior theoretical calculations (Allanore, Electrochimica Acta, 2013) that suggested an essential role of convection and electrolyte composition on the ability to sustain oxygen evolution at high current densities. In addition, the reported results show that electrochemical measurements in molten oxides coupled with mass-transfer models are complementary characterization tools for oxygen chemistry.

In recent years, researchers have incorporated mussel-inspired metal-coordinate cross-links into various types of gels to improve their mechanical properties, particularly toughness and self-healing. However, not much is understood about how the linear mechanical properties of these gels dictate their tack properties. In this study, we use shear rheology and tack tests to explore correlations between linear viscoelastic properties (i.e., plateau modulus, G p , and characteristic relaxation time, τ c ) and tack behavior (i.e., peak stress, σ max , and energy dissipation per volume, EDV) of transiently cross-linked hydrogels comprised of histidine-functionalized 4-arm PEG coordinated with Ni2+. By using the Ni2+-histidine ratio and polymer wt % of the transient networks to control their viscoelastic properties, we demonstrate a strong dependence of σ max on G p and τ c . The observed correlation between network dynamics and mechanics under tensile load is in good quantitative agreement with a theoretical framework for σ max , which includes the linear viscoelastic properties as parameters. EDV is also influenced by G p and τ c , and the EDV after reaching σ max is additionally dependent on the polymer wt %. These findings are consistent with previously proposed molecular mechanics of reversible His x Ni2+ cross-links and provide us with new insights into the correlations between bulk mechanics and adhesive dynamics of gels with transient metal-coordinate cross-links.

This has further inspired the creation of supramolecular networks where metal-coordination complexation is the sole crosslinking mechanism. These fully transient, musselinspired hydrogels typically comprise multiarm polymers, end-functionalized with metal-coordinating ligands, such as His or DOPA, with metal ions serving as the crosslinking sites. [2,[20][21][22] Both His and DOPA are bidentate ligands that can coordinate with metal ions in either tris-, bis-, or mono-modalities, or are left free (unbound) (Figure 1a). [2,4] The tris-and bis-modalities serve as crosslinking sites to create a percolated transient hydrogel network, while the mono-modality and free ligands do not support network formation. To coordinate with metal ions, ligands must be deprotonated, and the concentration of available deprotonated ligands relative to the concentration of available metal ions determines the distribution of ligand coordination modalities at equilibrium within the network. [9,10]